Patients that have respiratory difficulties often must be placed on a mechanical ventilator. These respiratory difficulties may be pathological in nature or may be due to the fact that the patient is too weak or sedated to independently perform respiration functions. Often, the patient may be spontaneously attempting to breathe but is not able to complete a full respiratory cycle. In these cases, mechanically assisted ventilation is provided. In some mechanically assisted ventilation platforms, a combination of pressure and/or flow sensors detect a patient's breath attempt. Detection of a breath attempt triggers the mechanical delivery of a breath. The breath is provided by the delivery of medical gases under a pressure that is sufficient to overcome the system resistance and the patient's airway resistance to fill the lungs in an inspiratory phase. When the pressure of the medical gas is reduced, the natural elasticity of the patient's chest wall forces the delivered breath out of the patient in an expiratory phase.
The medical gases supplied to the patient may comprise air, oxygen, helium, nitric oxide, anesthetic agent, drug aerosol, or any other gas breathed by the patient. Air is referred to as the drive gas for the ventilator system and any other medical gases are referred to as supplemental gases to the air.
The healthcare industry faces the challenge of providing higher quality care, while reducing the cost of providing that care. One aspect of the challenge to reduce cost is to reduce the fundamental costs that are associated with the provision of healthcare. Fundamental costs are the costs that are associated with the infrastructure needed to provide medical care to patients, for example, the costs of medical gas used to provide ventilatory support. Additionally, a need exists for an improved quality of care provided in remote locations such as military field hospitals, third world countries, and rescue or emergency situations. One aspect that is common to meeting these challenges is to provide equipment that is mobile. The mobility of a piece of equipment includes reducing the equipment's need for external components, such as tanks of medical gas, or an external medical gas supply. The increased mobility of a piece of equipment allows for it to be moved around a hospital to the area where it is currently needed and allows for a piece of equipment to be transported to a remote location where other less portable equipment is not available.
There are currently a wide variety of systems available to provide ventilatory support to a patient, or to provide anesthesia delivery to a patient. There are systems that combine both of these functionalities, as disclosed in U.S. Pat. No. 5,315,989, which is incorporated in its entirety herein; however, these systems require a supply of pressurized medical gas in order to provide the respiratory support to the patient. Medical gas is often supplied from pressurized supply tanks, or medical gas may be delivered to the ventilator via gas connections in the wall of a room in the hospital. Dependence upon fixed-location gas connections severely limits the portability of a ventilatory system as the system can only be used in those rooms that have been outfitted with medical gas supply lines, tapping into a centralized supply of medical gas. Furthermore, dependence upon medical gas supply lines increases the cost of adding additional rooms to a hospital facility since each of these new rooms must be connected to the centralized supply of medical gas and outfitted with the medical gas supply lines. Alternatively, smaller and thus more portable medical gas supply tanks may be used by an individual ventilatory system. However, these tanks are more expensive and, while mobile, are still cumbersome to transport.
A third type of ventilatory system currently available reduces the need for a supply of medical gas, where the medical gas to be used is air, by integrating a pump with the ventilatory system such that the pump pressurizes the ambient air to the pressure required by the ventilatory system. Ventilatory systems integrated with a high pressure pump for pressurizing ambient air suffer from limitations inherent with high pressure pumps. In general, high pressure pumps suffer from the fact that they are relatively large and heavy which thus reduces the portability of systems using these pumps. The weight of the pump is counter-productive as the implementation of a ventilatory system with a pump is generally for the purpose of making the ventilatory system a mobile one. Alternatively, non-high pressure pump systems (e.g., blower or turbine systems) generally have a slow response time for delivering the proper supply of medical gas to the patient at the proper time. To compensate for this, non-high pressure pump systems are used with complicated valves and circuitry, thus increasing the amount of power used to operate the ventilator system. This too is not desirable in a mobile ventilatory support system.
Therefore, a patient respiratory support system that can provide sufficient medical gas pressure to ensure proper patient ventilation, provide a fast response time to continually adjust the pressure delivered in conjunction with the patient's respiratory cycle, provide low power consumption, and reduced system size and weight is desirable. A patient's respiratory support system that uses a pump that combines these qualities would greatly increase the mobility of a patient respiratory support system, thus allowing greater flexibility in the locations where the patient may receive respiratory support.